To determine a link budget in a satellite communication system, there is typically an accounting for gains and losses from the transmitter, through the medium (e.g., the satellite communication link or links), and to the receiver in the system. A link budget, therefore, may account for performance of particular links, including the attenuation of the transmitted signal due to propagation and other miscellaneous gains and losses. Link performance may also be impacted by hardware in the system and the antenna gains at particular terminals. Time varying channel conditions, such as rain factors, may impact link performance as well. Randomly varying channel gains such as fading may be taken into account by adding some margin depending on the anticipated severity of its effects. The link performance of individual links are often characterized by the terminal's carrier-to-noise ratio (“C/N”). Link conditions may be determined for both uplinks and downlinks between terminals and a satellite.
Satellite communication systems may benefit from adapting signal characteristics (e.g., the modulation and coding of signals (“modcodes”)). The modcodes may be adapted on a per-terminal basis to better match the link conditions for each terminal in a multi-terminal system. For example, higher order modulation and higher code rate may allow more information to be transmitted over a given time, while lower order modulation and lower code rate may be more reliable but require more time to transmit the same size message.
Typically, to determine link performance, a return channel or other means may be used to report the conditions of a receiving terminal. This method may involve first setting up a link to the receiving terminal through a satellite. It may be beneficial to identify novel systems, devices, and methods to efficiently determine link performance for different links in a multi-terminal satellite system.